Delaminations in concrete bridge decks result primarily from corrosion of the reinforcing bars (or rebar). This corrosion leads to volumetric expansion of the rebar. When the rebar expands, concrete cracks, and there is a localized separation of the concrete cover from the underlying concrete. Impact-echo testing is an effective technique to map delaminations on concrete bridge decks. However, mapping speed is limited by necessary retrieval of the impactor for traditional tests. To achieve higher scanning speeds, it is advantageous to use both a non-contact measurement (air-coupled impact-echo) and disposable-impactor excitation. Disposable impactors have the potential advantage of achieving greater deck scanning speeds because they do not need to be retrieved, and they can also be used with air-coupled measurement systems. This thesis reports impact excitation of concrete using disposable impactors such as water droplets and ice balls. The impact characteristics of these impactors are compared with those of steel balls and chain links. Comparing the acoustic recordings on intact and delaminated concrete surface shows that water droplets and ice balls are able to excite flexural resonant modes associated with delamination defects. The use of water droplets and ice balls for shallow delamination detection in concrete is thus demonstrated.

En la presente tesis se efectúa un estudio del comportamiento térmico de tableros de puente a partir de los datos de su geometría, para lo cual es preciso definir una clasificación de los tableros de puente a efectos térmicos. Se introducen como condiciones de contorno los datos de la temperatura ambiente y radiación a lo largo del día. Para resolver la conducción de conducción de calor se han creado dos programas de ordenador que permiten obtener el campo de temperaturas en el tablero y se ha efectuado el consiguiente estudio paramétrico de los variables que influyen en el problema. Se propone una modificación del sistema de obtención del diagrama momentos-curvatura que considere el estado de auto tensión térmica.

Following development of rectangular prestressed, precast concrete panels (PCP) that could be used as stay-in-place formwork adjacent to expansion joints in bridge decks, the Texas Department of Transportation (TxDOT) initiated a research effort to investigate the use of PCP units at skewed expansion joints. The fabrication of trapezoidal PCP units was studied and the response of skewed panels with 45° and 30° skew angles was obtained. The panels were topped with a 4 in. thick cast-in-place (CIP) slab to complete the bridge deck. Specimens with 45° skew performed well under service and overload levels. The deck failed in diagonal shear at loads well over the design level loads. However, two 30° specimens failed prematurely by delamination between the topping slab and the PCP. The cause of the delamination was insufficient shear transfer capacity between the PCP and CIP topping slab. For the specimens tested at a square end, the failure mode was punching shear at high loads for all specimens. The surface condition of the PCP was specified to have a “broom finish” and the panel was to have a saturated surface dry (SSD) condition so that PCP units would not leach moisture from the CIP topping slab. Neither of these conditions was satisfied in the two panels that failed prematurely. Although the panels were specified to have a broom finish, the panel surface had regions that were quite smooth. The objective of this research project was to reinvestigate the response of 30° PCP at an expansion joint following specified procedures for finish and moisture conditions. One specimen was constructed with a rectangular panel placed between two 30° skewed panels. These panels had a much rougher surface texture than the previously tested panels that failed in delamination. The skewed ends of the specimen were subjected to monotonically increasing static loads at midspan of the panel ends. The panels failed in diagonal shear and the response of the tested specimen confirmed that the panel surface roughness, and not the skew angle, caused delamination with the previously tested specimens. While TxDOT does not currently specify a minimum panel surface roughness, a surface roughness of approximately 1/4 in. is required in some codes for developing composite action. In addition, wetting the panels to a SSD condition prior to placement of the topping slab further enhances shear transfer between the topping slab and the PCP. / text

In bridge deck concrete, early-age cracking can lead to substantial serviceability and structural integrity issues over the lifespan of the bridge. An understanding of the temperature, stress, and strength development of concrete can aid determining the early-age cracking susceptibility. This project, funded by the Texas Department of Transportation, evaluated these properties for various bridge deck materials and mixture proportions. The research presented in this thesis involved a laboratory testing program that used a combination of semi-adiabatic calorimetry, rigid cracking frame, free shrinkage frame, and match cured cylinder testing program that allowed the research team to simulate the performance of common bridge deck mixture designs under hot and cold weather conditions. In this program, the semi-adiabatic calorimetry was used, with previously generated models, to generate the temperature profile of the mixture. The rigid cracking frame and free shrinkage frame were used to evaluate the restrained stress development and the unrestrained volume changes, respectively, under the simulated temperatures. The match-cure cylinder testing program allowed the research team to generate a strength development profile for the concrete mixtures under the various simulated temperature profiles. Results from the laboratory program revealed that in hot weather simulations, ground granulated blast furnace slag mixtures developed the lowest stress / strength ratios, and in cold weather simulations, Class F fly ash mixtures developed the lowest stress / strength ratios. In general, use of SCMs and limestone coarse aggregate results in mixtures that generate less heat and lower stress / strength ratios. Isothermal testing showed that shrinkage reducing admixtures were effective in reducing early-age strains from chemical shrinkage. In addition to the laboratory testing program, a field testing program was completed to measure the temperature development of four bridge decks during the winter and summer months. The recorded concrete temperatures and the effects of the environmental conditions at the time of the pour will aid in the calibration and validation of the temperature prediction component of ConcreteWorks for bridge deck construction. In addition, experience gained through these field pours resulted in an optimized instrumentation procedure that will aid in the successful collection of data in future projects. / text

Cast-in-place concrete in composite with steel sections is commonly used in bridge deck constructions. The shear transfer between the concrete and steel section is achieved by shear connectors and the strength calculation of conventional shear connectors, i.e. shear studs, is provided in various design codes in North America. Due to the fact that the strength equation is largely based on experimental results, the applicability of the equation is only warranted where the design matches the experimental configuration of the test specimens. Thus, the codes specify detailing requirement for the stud height and the elevation of the reinforcement mesh in relation to the stud height. However, these requirements, in particular, the elevation of the reinforcement mesh, may be difficult to meet accurately in construction practice. The implications of not meeting the mesh requirement to the strength of the shear stud and the remedy solutions are examined in this study. An experimental program involving the test of thirty-three push-out specimens was designed and conducted with a focus on the shear studs' performance. Testing parameters included reinforcement mesh position, shear stud height, presence of stud head, shear stud spacing, and steel flange surface treatment. In addition, the performance of a new type of shear studs, referred to as adjustable studs, was also studied experimentally. The ultimate load and load vs. slip curves were presented and discussed in the forms of tables and graphs. The failure modes were noted and the relationship between the failure modes and the ultimate capacity was discussed. Ultimate loads obtained from specimens were then used to assess the efficacy of code suggested values. Results showed that depending on the elevation of reinforcement mesh, three failure modes were observed including concrete related failure, combined concrete failure and bent studs and stud shear-off from the steel flange. The elevation of the reinforcement mesh had a significant effect on the ultimate load of the specimen. As the mesh elevation increased from intercepting the stud to being in flush with the top of the stud to above the stud, the ultimate load decreased. Specimens with unheaded shear studs had lower ultimate load than specimens with headed shear studs. Flange treatment had an impact on the ultimate load, where the coating on flanges resulted in a decrease in the ultimate load. Test results also showed that the close placement of the shear studs result in a reduction on the ultimate load when the other parameters were kept the same. In the comparison between conventional and adjustable shear studs, specimens with adjustable studs shared similar failure mode to those with conventional studs, but attained on average lower load capacity. The comparison with the code suggested values showed that the code suggested value is only ensured when double-layer reinforcement mesh is used and placed at code specified elevation. A single layer mesh intercepting the studs resulted in the ultimate load slightly lower than the code value. The code values for adjustable studs are markedly higher than the experimental value, which raises the question whether the code equation for conventional studs is directly transferrable to adjustable studs.

Deterioration of concrete bridge decks has become a serious problem in the past few decades. Fortunately, non-corrosive, light-weight Fiber Reinforced Polymer (FRP) material provides an excellent alternative. More than 117 bridges in the USA have been built or repaired with FRP. In Canada, no FRP bridge deck has been used in the field, yet. However, Wardrop Engineering Inc., Faroex Ltd., and ISIS Canada have successfully designed, manufactured, and patented the filament-wound Glass Fiber Reinforced Polymer (GFRP) bridge deck. Since there is no design code for FRP bridge decks, a finite element method, labeled “L&D”, is proposed in this thesis to help bridge engineers better understand the structural behavior of FRP bridge decks. The L&D method is validated by comparing the analysis results with the experimental results of three filament-wound GFRP bridge decks. This L&D method is also applicable for analyzing FRP bridge decks manufactured by other processes.

Deterioration of concrete bridge decks has become a serious problem in the past few decades. Fortunately, non-corrosive, light-weight Fiber Reinforced Polymer (FRP) material provides an excellent alternative. More than 117 bridges in the USA have been built or repaired with FRP. In Canada, no FRP bridge deck has been used in the field, yet. However, Wardrop Engineering Inc., Faroex Ltd., and ISIS Canada have successfully designed, manufactured, and patented the filament-wound Glass Fiber Reinforced Polymer (GFRP) bridge deck. Since there is no design code for FRP bridge decks, a finite element method, labeled “L&D”, is proposed in this thesis to help bridge engineers better understand the structural behavior of FRP bridge decks. The L&D method is validated by comparing the analysis results with the experimental results of three filament-wound GFRP bridge decks. This L&D method is also applicable for analyzing FRP bridge decks manufactured by other processes.

Ultra-high performance concrete (UHPC) was evaluated as a potential material for future bridge deck designs. Material characterization tests took place to identify potential challenges in mixing, placing, and curing UHPC. Biaxial testing was performed to evaluate behavior of UHPC in combined tension and compression stress states. A UHPC bridge deck was designed to perform similarly to a conventional concrete bridge deck, and a single unit bridge deck section was tested to evaluate the design methods used for untreated UHPC. Material tests identified challenges with placing UHPC. A specified compressive strength was determined for structural design using untreated UHPC, which was identified as a cost-effective alternative to steam treated UHPC. UHPC was tested in biaxial tension-compression stress states. A biaxial test method was developed for UHPC to directly apply tension and compression. The influence of both curing method and fiber orientation were evaluated. The failure envelope developed for untreated UHPC with random fiber orientation was suggested as a conservative estimate for future analysis of UHPC. Digital image correlation was also evaluated as a means to estimate surface strains of UHPC, and recommendations are provided to improve consistency in future tests using DIC methods. A preliminary bridge deck design was completed for untreated UHPC and using established material models. Prestressing steel was used as primary reinforcement in the transverse direction. Preliminary testing was used to evaluate three different placement scenarios, and results showed that fiber settling was a potential placement problem resulting in reduced tensile strength. The UHPC bridge deck was redesigned to incorporate preliminary test results, and two single unit bridge deck sections were tested to evaluate the incorporated design methods for both upside down and right-side up placement techniques. Test results showed that the applied design methods would be conservative for either placement method. / Ph. D.

The main goal of this diploma thesis is a design and verification of a steel footbridge crossing the river Dřevnice in Zlín. As the basic material steel S355 and for selected members steel S235 was chosen. There are two structural variants designed in the introductory part of the thesis. These variants are then compared and in the next part only selected, more favourable variant, is addressed. The selected variant is a truss footbridge with a bridge deck at the bottom and curved top chords. The bridge deck consists of floor beams and steel plate with longitudinal stiffeners. The span of the structure is 35.0 m, the width of the footbridge is 3.9 m and its height in the middle of the span is 4.2 m.

Master´s thesis describes the design of the railway bridge in Ústí nad Labem. Length of the structure is 200.00 meters, the height of the structure is 32.61 m and width of the structure is 12.10 m. Main structural system is composed of a spatial strut-frame structures. The bridge carries an important railway stations between Usti nad Labem Západ, Usti nad Labem Střekov. Part of the proposal is a footbridge for pedestrians.